1. Technical Field
This invention relates in general to processing devices and, more particularly, to application scheduling with energy awareness.
2. Description of the Related Art
In the technical worlds of computing and communications, the fastest evolving technologies involve mobile devices that combine communications and computing functions. New appliances are evolving very quickly, shifting from proprietary environments to open platforms conformance, and, with the arrival of third generation (3G) wireless networks, supporting new applications like multimedia players. But processing requirements to support this new flexibility and new applications are far higher than performances that actual appliances are able to provide. Accordingly, new hardware platforms with more powerful processors have been introduced. But these appliances must deal with embedded systems constraints, mainly power consumption, since powerful processors are generally power hungry components.
Energy consumption is very important to consumers, since mobile devices, such as smart phones, cellular phones, PDAs (personal digital assistants), and handheld computers, command a premium price in order to function apart from a wired power connection. Additionally, size plays an important factor in a consumer's choice of a mobile device and, therefore, the size of the battery is limited. Therefore, it is a high priority for manufacturers to produce devices with long battery lives, without resorting to large battery sizes.
A way to achieve the tradeoff between low power consumption and high performances computations is to use heterogeneous multiprocessor platforms, like OMAP. Several processors in parallel provide the same performance than a uniprocessor platform while using a lower clock frequency, thereby allowing a lower power supply and finally a lower power consumption.
But for a hardware platform to solve the problem of the power consumption, it must have strong software support. Most applications are not designed for multiprocessor platforms, so they cannot exploit the parallelism of the platform. Even if applications express their internal parallelism, a software mechanism is needed to perform computation distribution over processors. Moreover, the evolution of wireless appliances towards open environments, which allows dynamic downloading of unknown applications, prevents usage of precomputed placements.
Therefore, a need has arisen for a method and apparatus for controlling the execution of applications in a mobile communication device to reduce energy consumption.